Wind energy may be used to power ships, mills, pumps or generators. The best known of these machines may be the propeller drive with two, three or more blades mounted vertically on top of a pillar, with the possibility of turning in the direction of the wind action.
However, all of these devices may operate in the free stream of the wind. Wind turbines may be used for the generation of electrical energy. In a typical form, a multi-blade turbine may be rotatably mounted on a support such as a pole or tower to be driven by surface wind, the turbine in turn driving an electrical generator coupled, for example, to electrical utility lines. The turbine may be rotated about a vertical axis of the pole or tower to compensate for shifts in wind direction. Diffusers may be used to increase the power output of converting wind energy to electrical energy. The disadvantage with such wind turbines may be that the magnitude of the energy produced in relation to the size of a plant is relatively small. A highly optimized diffuser may be needed to optimize the output of energy.